IBAN validation with no network call: ISO 13616 length and structure for every country in the SWIFT IBAN registry, the mod-97 checksum, national check digits where a public algorithm exists (FR, ES, IT, BE, NL, NO, FI, PL, PT and the Balkan countries), and the split into bank code, branch code and account. Returns the electronic and print format. Pass ibans= for up to 50 at once. No bank name or BIC lookup (no dataset is bundled). Price: $0.001 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.